Ad-aware se plus- this will be a nice gift for someone who is an ad-aware follower but not for your set-up.

Prevx1- if you get the same email as everyone else you should get 2 keys for this. Maybe you'll like the windows firewall/prevx1 combo but read further.

Earlydetection Center 2.0- pawn this off on someone...as a gift.

A-squard Anti-malware 2.1- tremendous realtime protection but a rather high false positive rate for an elite product. But this would be fine for a windows firewall/prevx1/a-squared combo.

Online Armor V2- do not miss out on the opportunity to try this product out. Find the OA thread under "other firewalls" and ask for a 30 day evaluation of OA2. I think you will be very glad you did. The program is lightweight, powerful, provides great protection. And this product probably exceeds the windows firewall/prevx1/a-squared combo above.

Spy Sweeper for MSN (through ISP)- as long as their AV is not involved this is a great product. It has a powerful realtime shield and nice detection/removal ability. A-squared may have a better realtime shield but because of the false positives I would probably give SS the edge. But if you have a key for A-Squared, why not just use SS as your on demand scanner?

windows anti-spyware(free)- this product is not worth the trouble.

In all, I would recommend you go with OA2 and use SS for on-demand. You may be able to run them both without conflict. Try them out as I believe they all have free trial periods from their websites. Although you'll need to get a link for OA2. Every computer is different and you need to see what you feel most comfortable with. I have tried them all and OA2 may be the best firewall I have ever used- ZA Pro, Comodo, ect included. So be sure and try that product out. The A-Squared product comes with very high marks as well, more for realtime protection, though.

Prevx1 i also have to suggest. I thought i seen it all untill installed this one. It is nothing short of notorious on malware and watches over your system like a rattlesnake. Plus you can't go wrong with it's huge global community support which feeds the database. Awesome.

quick question though, I am under a router(westell 327w) with hardware firewall (default setting low)+windows firewall. How much more protection can OAv2 built-in firewall give me? Would these extra benefits weigh over the easy use of windows firewall offers?
thx a bunch.

With OA2 you get inbound and outbound protection. Windows firewall only provides inbound protection. You would be much better off turning off Windows firewall and using OA2. Also, OA2 works really well in default mode. So there are no adjustment needed, just allow programs access like any other new firewall. Otherwise its out of box settings work quite well.

Just some food for thought. BoClean is very renown and respected by many users also and is said to become released as freeware courtesy of a recent acquisition by the COMODO firewall group. You might keep an eye out for it.
I read sparkling reviews of it's abilities for quite some time now.